<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
  <style>
    span{
      color: #ff0000;
    }
  </style>
  <link rel="stylesheet" href="../CSS/demo.css">
</head>
<body>
<!--方式1-->
<div style="color: crimson">
  hello CSS
</div>
<!--方式2-->
<span>hello CSS</span>

<!--方式3-->
<h1>hello CSS</h1>
</body>
</html>